This Application claims priority of the People's Republic of China Patent Application No. 201210472208.4, filed on Nov. 9, 2012, the entirety of which is incorporated by reference herein.
Field of the Invention
The present disclosure relates to a touch-sensing apparatus; and more particularly, to a touch-sensing electrode structure and a method of manufacturing the same.
Description of the Prior Art
With the advancement of technology, many electronic products have discontinued use of traditional input devices such as keyboards or mouses in favor of touch panels. Existing touch panels generally use the following methods for sensing touch: capacitive sensing, resistive sensing, surface acoustic wave technology, infrared sensing, etc. Capacitive sensing is the most commonly used method.
A capacitive touch panel usually includes a substrate, a sensing electrode disposed on the substrate, and metal signal-transmitting wires disposed at the peripheral region of the substrate. The sensing electrode near the peripheral region is formed by a main body and a connecting portion connected to an end of the main body. The width of the connecting portion is smaller than half the width of the end of the main body. The signal-transmitting wires are each formed by a head portion and a tail wire. The head portions of the signal-transmitting wires are superimposed on the corresponding connecting portions of the sensing electrodes. The head portions of the signal-transmitting wires and the connecting portions of the sensing electrodes have similar sizes. Capacitive touch panels are attached on electronic devices as touch-sensing apparatuses for users to operate with. Given that a gap exists between the touch panel and the electronic device, a user can easily transfer static electricity from his body into the gap during operation, accumulating electricity on the peripheral region of the touch panel. Additionally, a large amount of static electricity in the air also accumulates on the peripheral region of the touch panel. Therefore the effect of static electricity on the connecting portion of the electrode and the signal-transmitting wires at the peripheral region is increased.
According to Joule's Law: Q=I2Rt, static electricity passing through signal-transmitting wires or sensing electrodes produces heat. Given that impedance of metal signal-transmitting wires is smaller (approximately several hundred Ohms), the heat generated by static electricity passing through the metal signal-transmitting wires is not sufficient to burn the wires. However, the higher impedance of the connecting portions of the sensing electrodes (approximately several thousand Ohms) results in generating more heat. Given that the width of the connecting portion is smaller than half the width of the end of the main body, if other parameters (such as length and height) are constant, the limited cross-sectional area of the connecting portion of the sensing electrode causes the static electricity distributed on an unit area to be high, such that the connecting portion of the sensing electrode is burned due to difficulty in dissipating the heat generated thereat. Consequently, circuits are shorted and the touch panel is busted. Therefore, this type of capacitive touch panel is vulnerable to static electricity.